The present disclosure relates to an apparatus and method for coating substrates using an ESC and Van der Waals forces.
Handheld display glass with surface treatments is being developed to meet market demands, and such surface treatments include antimicrobial surface treatments and scratch resistant optical coatings. There exists a need for the combination of low manufacturing cost and rapid delivery of such handheld displays and therefore a low-cost, high-volume manufacturing process for producing high performance scratch-resistant optical coatings is desired for both 2D and 3D glass substrates. Such manufacturing processes include vacuum deposition processes in which the substrates reach a relatively high processing temperature due to particle kinetics over the process duration (e.g., up to or even exceeding 230° C.), which makes clamping the substrates difficult with conventional techniques, such as adhesive tapes.
The use of adhesive tapes to secure substrate for coating in those processes utilizing a vacuum deposition process involves three distinct disadvantages: (1) the taping process is labor intensive and increases the time to set up the substrates for each subsequent run and (2) the adhesive outgases in the pristine plasma environment resulting in contamination, requiring vacuum deposition chambers to be cleaned periodically which, turn adds more cost and time to the process, and, (3) the adhesive leaves residue on the coated substrate, which requires additional handling and cleaning post-coating, also adding further costs and time to the process.
Several methods to bond substrates temporarily for vacuum deposition processing have been tried in industry without significant success. These methods include the use of glass-to-glass Van der Waals bonding, the use of adhesive bonding using various adhesive compositions, and the use of polymeric coatings on the substrate surface to change the surface energy resulting in a temporary bond remaining strong enough for the contemplated end process but weak enough to de-bond once the process is complete. To initiate a Van der Waals bond between a glass carrier and a glass substrate typically requires firm and uniform pressure over the entire contact area. It is not desirable in the production process to apply such forces or to even contact the substrate surface to be coated since this action directly impacts the resulting coating quality.
Accordingly, it can be seen that a need remains for a satisfactory low-cost technique for attaching glass substrates in vacuum deposition chambers for coating using a vacuum deposition process.